Design, Synthesis and Insecticide Activity of Novel Acetylcholinesterase Inhibitors: Triazolinone and Phthalimide Heterodimers

Target-Based Design, Synthesis, and Biological Evaluation of Novel 1,2,4-Triazolone Derivatives as Potential nAChR Modulators

Novel agrochemicals have been successfully developed using target-based drug design (TBDD). To discover a novel, efficient, and highly selective nicotinic insecticide candidate, we developed a unified pharmacological model using TBDD by studying the binding modes of 11 nicotinic acetylcholine receptor (nAChR) modulators with acetylcholine binding protein (AChBP) targets for the first time. This model was used to design and develop a series of 1,2,4-triazolone derivatives. Bioassays demonstrated excellent insecticidal activities against Aphis glycines of compounds 4k (LC50 = 4.95 mg/L) and 4q (LC50 = 3.17 mg/L), and low toxicities to Apis mellifera. Additionally, compound 4q was stably bound to Aplysia californica AChBP, which was consistent with the pharmacological model obtained via molecular docking and molecular dynamics simulations. Therefore, compound 4q could be a potential lead candidate targeting nAChR. The explicit pharmacological model of nAChR modulators with Ac-AChBP in this study may facilitate the future rational design of eco-friendly nicotinic insecticides.

Toward the cholinesterase inhibition potential of TADDOL derivatives: Seminal biological and computational studies

Alzheimer's disease (AD) is a degenerative neurological disease characterized by gradual loss of cognitive skills and memory. The exact pathogenesis involved still remains unrevealed, but several studies indicate the involvement of an array of different enzymes, underlining the multifactorial character of the disease. Inhibition of these enzymes is therefore a powerful approach in the development of AD treatments, with promising candidates, including acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), and monoamine oxidase. Interestingly, AChE is the target of a major pesticide family (organophosphates), with several reports indicating an intersection between the pesticide's activity and AD. In this study, various TADDOL derivatives were synthesized and their in vitro activities as AChE/BuChE inhibitors as well as their antioxidant activities were studied. Molecular modeling studies revealed the capability of TADDOL derivatives to bind to AChE and induce inhibition, especially compounds 2b and 3c furnishing IC₅₀ values of 36.78 ± 8.97 and 59.23 ± 5.31 µM, respectively. Experimental biological activities and molecular modeling studies clearly demonstrate that TADDOL derivatives with specific stereochemistry have an interesting potential for the design of potent AChE inhibitors. The encouraging results for compounds 2b and 3c indicate them as promising scaffolds for selective and potent AChE inhibitors.

A tacrine-tetrahydroquinoline heterodimer potently inhibits acetylcholinesterase activity and enhances neurotransmission in mice

Cholinergic neurons are ubiquitous and involved in various higher brain functions including learning and memory. Patients with Alzheimer's disease exhibit significant dysfunction and loss of cholinergic neurons. Meanwhile, such cholinergic deficits can be potentially relieved pharmacologically by increasing acetylcholine. Acetylcholinesterase (AChE) inhibitors have been used to improve cholinergic transmission in the brain for two decades and have proven effective for alleviating symptoms in the early stages of Alzheimer's disease. Therefore, the search for AChE inhibitors for drug development is ongoing. The enzymatic pocket of AChE has long been the target of several drug designs over the last two decades. The peripheral and catalytic sites of AChE are simultaneously bound by several dimeric molecules, enabling more-efficient inhibition. Here, we used 6-chlorotacrine and the tetrahydroquinolone moiety of huperzine A to design and synthesize a series of heterodimers that inhibit AChE at nanomolar potency. Specifically, compound 7b inhibits AChE with an IC₅₀ < 1 nM and spares butyrylcholinesterase. Administration of 7b to mouse brain slices restores synaptic activity impaired by pirenzepine, a muscarinic M1-selective antagonist. Moreover, oral administration of 7b to C57BL/6 mice enhances hippocampal long-term potentiation in a dose-dependent manner and is detectable in the brain tissue. All these data supported that 7b is a potential cognitive enhancer and is worth for further exploration.

A structural analysis of 2,5-diaryl-4H-2,4-dihydro-3H-1,2,4-triazol-3-ones: NMR in the solid state, X-ray crystallography, and GIPAW calculations

The ¹ H, ¹³ C, ¹⁵ N, and ¹⁹ F nuclear magnetic resonance (NMR) spectra of 11 2,5-diaryl-2,4-dihydro-3H-1,2,4-triazol-3-ones have been acquired in DMSO-d₆ solution and the ¹³ C, ¹⁵ N, and ¹⁹ F NMR spectra have also been acquired in the solid state (solid-state nuclear magnetic resonance [SSNMR] and magic angle spinning [MAS]). The X-ray structures of Compounds 3, 5, and 6 have been determined by X-ray diffraction. Theoretical calculations at the gauge-independent atomic orbital (GIAO)/B3LYP/6-311++G(d,p) level have provided a set of 321 chemical shifts that were compared with 310 experimental values in DMSO-d₆ . To obtain good agreements, some effects need to be included. The SSNMR chemical shifts have been compared with gauge-including projector-augmented wave (GIPAW) calculations and with the heavy atom-light atom (HALA) effects.